Ignition device for internal combustion engine

#The present invention relates to an igniter for controlling a primary current to be turned on or off, which is used with an ignition device for internal combustion engine, and more particularly to an ignition device for internal combustion engine in which an igniter and an ignition coil are integrated within an ignition device case.

#Conventionally, there is proposed an ignition device for internal combustion engine in which an igniter and an ignition coil are equipped within the same ignition device case. Particularly in recent years, the ignition device arranged for each ignition plug is spread. FIG. 5 shows the structure of an igniter for use with this ignition device, and FIG. 6 show a method of mounting the igniter on the ignition coil of the ignition device for internal combustion engine. As previously described, the ignition coil and the igniter are indispensable for each other and employed as a set in the ignition device for internal combustion engine.

#In FIGS. 5 and 6, the ignition device has a primary coil and a secondary coil buried in a plug hole provided in an engine main body, not shown, in which an igniter 10 is disposed directly above the coil portion and outside the plug hole, these being accommodated within an ignition device case. As shown in FIG. 5, the igniter 10 is connected to a connector 1 having an external connection terminal 2 for supplying the power from a battery or the like, and an igniter metal terminal 9 connected to the external connection terminal 2. A cover 11 made of an elastic material such as resin is put on the igniter 10, and a filling epoxy resin is filled in the entity of the igniter 10 and cured to have the finished product.

#FIG. 1 is a cross-sectional view of the structure of an igniter according to a first embodiment of the present invention.

#FIG. 2 is a cross-sectional view of the igniter of FIG. 1 mounted on an ignition device.

#FIG. 3 is a cross-sectional view of the structure of an igniter according to a second embodiment of the invention.

#Referring to FIG. 1, a first embodiment of the present invention will be described below. In this invention, an igniter is not a package product such as a general-purpose power transistor or IGBT, but a component before molding in which a driving element 6 is arranged on an internal wiring substrate. Further, an ignition device of this invention is composed of the igniter and an ignition coil 13, both of which are accommodated within the same ignition device case, in which the igniter is contained in an igniter case and filled with a molding resin.

#In FIG. 1 representing the first embodiment of the invention, the igniter comprises an internal wiring substrate 5 made of ceramics and formed of alumina, which has a driving control IC. The internal wiring substrate 5 has a circuit pattern printed and the electronic components mounted to provide the additional functions, and bonded on a heat sink for heat radiation 4 by adhesives. On the surface of the heat sink 4, the driving element 6 consisting of a Darlington transistor for making switching drive to turn on or off the primary current is disposed. The driving element 6 may consist of IGBT. The internal wiring substrate 5 and these components making up the igniter, such as the driving element 6 and the heat sink for heat radiation 4 are accommodated within the igniter case 8 formed of plastic such as PPO, PPT, PBT and PET. The igniter case 8 has the connector 1 for connecting to the external connection terminal 2, the igniter and the external connection terminal 2 being integrally molded. The igniter components accommodated within the igniter case 8 and the external connection terminal 2 are electrically connected by a bonding wire 3, and the igniter is molded by a molding resin 7 with the igniter case 8 as the outer packaging after wire bonding.

#The igniter that is molded with the igniter case 8 as the outer packaging is placed in an igniter mounting space within the ignition device case, as shown in FIG. 2. Since the external connection terminal 2 is already formed integrally with the igniter case 8, there is no need for the connector 1 as a separate part and the step of welding the igniter and the connector, resulting in the smaller number of parts and the reduced number of steps.